U.S. patent application number 12/408749 was filed with the patent office on 2009-09-24 for electronic device.
This patent application is currently assigned to FUJITSU LIMITED. Invention is credited to Kenji KOBAE.
Application Number | 20090236127 12/408749 |
Document ID | / |
Family ID | 41087761 |
Filed Date | 2009-09-24 |
United States Patent
Application |
20090236127 |
Kind Code |
A1 |
KOBAE; Kenji |
September 24, 2009 |
ELECTRONIC DEVICE
Abstract
An electronic device comprises a substrate; a wiring pattern
which is provided on a front surface of the substrate, and which
includes a plurality of connection ends; a circuit component which
houses a circuit, and which includes bumps, electrically connected
to the circuit, that project from a specific surface of the circuit
component, and which is disposed with the specific surface facing
the front surface of the substrate; conductive members which
electrically connect the bumps of the circuit component and the
connection ends of the wiring pattern, and which fix the circuit
component to the substrate; and guide sections which are provided
on the substrate, and to each of which the conductive member forced
out of an interval above the corresponding connection end is guided
to prevent the conductive member from reaching a connection end
other than the corresponding connection end.
Inventors: |
KOBAE; Kenji; (Kawasaki,
JP) |
Correspondence
Address: |
Fujitsu Patent Center;C/O CPA Global
P.O. Box 52050
Minneapolis
MN
55402
US
|
Assignee: |
FUJITSU LIMITED
Kawasaki
JP
|
Family ID: |
41087761 |
Appl. No.: |
12/408749 |
Filed: |
March 23, 2009 |
Current U.S.
Class: |
174/255 |
Current CPC
Class: |
H01L 2224/83051
20130101; Y02P 70/611 20151101; H01L 2924/00014 20130101; G06K
19/0775 20130101; H01L 2924/15151 20130101; H01L 2224/27013
20130101; H01L 24/29 20130101; H05K 2201/09036 20130101; H05K
2201/09781 20130101; H05K 2201/09063 20130101; H05K 2201/10674
20130101; H01L 2224/293 20130101; H01L 24/16 20130101; H05K 3/321
20130101; Y02P 70/50 20151101; G06K 19/07749 20130101; H01L
2224/2929 20130101; H01L 2224/83851 20130101; H01L 23/13 20130101;
H01L 2224/16225 20130101; H01L 2224/16227 20130101; H05K 2201/09381
20130101; H01L 2924/00011 20130101; H01L 2224/81903 20130101; H05K
1/111 20130101; H01L 2924/00011 20130101; H01L 2224/29075 20130101;
H01L 2924/00014 20130101; H01L 2224/0401 20130101 |
Class at
Publication: |
174/255 |
International
Class: |
H05K 1/02 20060101
H05K001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 24, 2008 |
JP |
2008-076179 |
Claims
1. An electronic device comprising: a substrate; a wiring pattern
which is provided on a front surface of said substrate, and which
includes a plurality of connection ends; a circuit component which
houses a circuit, which includes bumps projecting from a specific
surface and electronically connected to the circuit on the specific
surface of said circuit component, and which is disposed with the
specific surface facing the front surface of said substrate;
conductive members which electrically connect the bumps of said
circuit component and the connection ends of said wiring pattern,
and which fix said circuit component to said substrate; and guide
sections which are provided on said substrate, and to each of which
the conductive member forced out of the interval above the
corresponding connection end is guided to prevent the conductive
member from reaching a connection end other than the corresponding
connection end.
2. An electronic device as defined in claim 1, wherein at least one
of said guide sections is a substrate portion in which a recess for
the conductive member to flow thereinto is formed in said
substrate.
3. An electronic device as defined in claim 1, wherein at least one
of said guide sections is a substrate portion in which a
penetrating hole for the conductive member to flow thereinto is
formed in said substrate.
4. An electronic device as defined in claim 1, wherein at least one
of said guide sections is a dummy pattern which is provided on said
substrate in juxtaposition to the connection end and in a manner to
be spaced away from the connection end.
5. An electronic device as defined in claim 1, wherein at least one
of said guide sections is a dummy wiring line which is laid in
continuation to the connection end on said substrate.
6. An electronic device as defined in claim 1, wherein at least one
of said guide sections is provided at a periphery of the
corresponding connection end and on a side away from the other
connection end.
7. An electronic device as defined in claim 1, wherein at least one
of said guide sections is provided at a periphery of the
corresponding connection end and on a side near to the other
connection end.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Application No. 2008-76179
filed on Mar. 24, 2008, the entire contents of which are
incorporated herein by reference.
FIELD
[0002] The present invention relates to an electronic device
wherein a circuit component having a built-in circuit is packaged
on a wiring substrate.
[0003] Heretofore, various RFID (Radio Frequency Identification)
tags which exchange information with external equipment such as a
reader/writer, in non-contact fashion with electric waves, have
been extensively employed. Many of such RFID tags have a structure
wherein a circuit component having a built-in circuit for
communicating through an antenna pattern with the external
equipment as stated above is packaged on a wiring substrate in
which the antenna pattern for the electric wave communications is
provided on a base made of plastic. Also, the connection between
the antenna pattern and the circuit built in the circuit component
is performed by the electrical connections between bumps being
minute terminals, which are provided in the circuit component and
which are electrically joined to the built-in circuit, and the
connection ends of the sides of the antenna pattern.
[0004] The electrical connections between the bumps and the
connection ends have hitherto been performed by a so-called
"pressure-welding method" wherein, after the circuit component has
been arranged on the wiring substrate so that the bumps may touch
the connection ends, this circuit component is pressed against the
wiring substrate under a specific pressure (refer to, for example,
Patent Document 1 being Japanese Laid-open Patent Publication No.
H06-232204). Here, in recent years, the circuit component has been
rapidly miniaturized, and the bumps provided in the small-sized
circuit component have become very minute. As a result, it has been
required in the pressure-welding method to pressure-weld the minute
bumps to the connection ends under a very low load. With
conventional pressure-welding methods, however, it has been
difficult to stabilize the low loads, and the problem of contact
malfunctions ascribable to the difficulty often occurs.
[0005] Especially in the RFID tag, the antenna pattern is sometimes
formed of a pattern of aluminum. With the aluminum pattern,
however, an electrical connectivity is liable to degrade due to
surface oxidation, and the problem as stated above occurs easily.
In the RFID tag, therefore, the pressure-welding method has a
narrow margin for the low load for favorably connecting the bumps
to the connection ends, and this incurs such a factor for the
increase of a cost that a special installation for achieving the
favorable connections is necessitated.
[0006] Meanwhile, as an example of a technique for connecting two
conductors in an electrically favorable state, there has been known
a technique wherein the two conductors are bonded to each other
with a member of anisotropic conductive resin which, when
interposed between the conductors, conducts a current only in a
direction coupling the conductors to each other. In accordance with
such a technique employing the anisotropic conductive resin member,
even when degradation of the electrical connectivity has occurred
due to the surface oxidation, the anisotropic conductive resin
member can compensate for such degradation. Also, many of the
circuit components have a plurality of bumps, and a plurality of
connection portions based on the one-to-one electrical connections
of the plurality of bumps and the plurality of connection ends are
formed by mounting the circuit component on the wiring substrate.
On this occasion, short-circuiting needs to be avoided between the
plurality of connection portions. Here, a conductivity exists in
only the interposition direction in the anisotropic conductive
resin member. Therefore, even when, for example, the anisotropic
conductive resin members have been roughly bonded so as to
encompass the connection portions, the connections of the
individual connection portions can be achieved while maintaining
the insulation between the connection portions. In this manner, the
bonding based on the anisotropic conductive resin members has also
the merit that the connections that avoid short-circuiting between
the connection portions can be performed with ease.
[0007] In the anisotropic conductive resin, the conductivity in the
interposition direction is achieved by conductive particles
dispersed in the resin. As a result, point connections through the
conductive particles become predominant in the connections between
the conductors based on such a technique. Therefore, when the
bonding which employs the anisotropic conductive resin is applied
to the connection in which a contact area is originally small as in
the connection between the minute bump and the connection end, a
sufficient number of point connections might not be obtained in the
small contact area, and it is unreasonable to apply the bonding
employing the anisotropic conductive resin, to such a connection of
small touch area.
[0008] Also, as a technique for enhancing the electrical
connectivity between two conductors, there has been known a
technique wherein the conductors are bonded by a conductive member
which is represented by a conductive adhesive, for example, a
solder paste or a silver paste (refer to, for example, Patent
Document 2 being Japanese Laid-open Patent Publication No.
10-4122). Also in the conductive member, conductivity is achieved
by conductive particles dispersed in a bonding resin. Since,
however, these conductive particles are much smaller than the
conductive particles in the anisotropic conductive resin, a
favorable connectivity can be attained also for the connection of
the small contact area as stated before. However, the conductive
member does not have the anisotropy of the conductivity as in the
anisotropic conductive resin. Therefore, in the case of connecting
the plurality of bumps to the conductor pattern as stated before,
the bondings can only be performed in individual connection
portions in order to avoid short-circuits between the plurality of
connection portions. Nevertheless, bondings which avoid the
short-circuiting between the connection portions are difficult
because, in the miniaturization of the circuit component as stated
before, not only are the individual bumps minute, but also the
intervals between the bumps are narrow.
[0009] In this regard, there has been proposed, for example, a
technique wherein grooves or penetrating holes are provided in a
wiring substrate, between individual connection ends which are
respectively connected with bumps, and conductive members in
individual connection portions are separated from each other based
on the idea that the conductive members have difficulty entering
the grooves or the penetrating holes (refer to, for example, Patent
Document 3 being Japanese Laid-open Patent Publication No.
2005-150652).
[0010] Also, there has been proposed, for example, a technique
wherein, in order to widen the interval between a circuit component
and a wiring substrate when the circuit component is mounted on the
wiring substrate, the amount the bumps provided in the circuit
component protrude from the circuit component is enlarged, thereby
to reduce the amount in which conductive members in individual
connection portions are peripherally enlarged when pressed by the
circuit component, and to avoid the contact between such conductive
members (refer to, for example, Patent Document 4 being Japanese
Laid-open Patent Publication No. 2001-102715).
SUMMARY
[0011] An electronic device comprises a substrate; a wiring pattern
which is provided on a front surface of the substrate, and which
includes a plurality of connection ends; a circuit component which
houses a circuit, and which includes bumps, electrically connected
to the circuit, that project from a specific surface of the circuit
component, and which is disposed with the specific surface facing
the front surface of the substrate; conductive members which
electrically connect the bumps of the circuit component and the
connection ends of the wiring pattern, and which fix the circuit
component to the substrate; and guide sections which are provided
on the substrate, and to each of which the conductive member forced
out of an interval above the corresponding connection end is guided
to prevent the conductive member from reaching a connection end
other than the corresponding connection end.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIGS. 1A and 1B are a schematic top view and a sectional
view, respectively, illustrating a first embodiment of an RFID tag
for an electronic device;
[0013] FIGS. 2A and 2B are a schematic top view and a sectional
view, respectively, illustrating a second embodiment of an RFID tag
for an electronic device;
[0014] FIGS. 3A and 3B are a schematic top view and a sectional
view, respectively, illustrating a third embodiment of an RFID tag
for an electronic device; and
[0015] FIGS. 4A and 4B are a schematic top view and a sectional
view, respectively, illustrating a fourth embodiment of an RFID tag
for an electronic device.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0016] Here, regarding the fundamental aspect of the electronic
device stated above, the following applied aspects are
preferable:
[0017] At least one of the guide sections is a substrate portion
where a recess into which the conductive member flows is formed in
the substrate, and
[0018] at least one of the guide sections is a substrate portion
where a penetrating hole into which the conductive member flows is
formed in the substrate.
[0019] According to the preferable applied aspects, the conductive
member can be drawn into the recess or the penetrating hole by
capillarity, and hence, the conductive member can be effectively
guided.
[0020] Also, regarding the fundamental aspect of the electronic
device, the following applied aspect is preferable:
[0021] "At least one of the guide sections is provided in the
periphery of the connection end and on a side away from another
connection end".
[0022] According to the preferable applied aspect, the conductive
members corresponding to the plurality of connection ends may be
guided in directions away from each other, and hence, the safer
mounting of the circuit component is possible.
[0023] First of all the fundamental aspect and a first embodiment
which is a practicable embodiment of the electronic device
according to the applied aspects will be described.
[0024] FIGS. 1A and 1B are pattern views illustrating an RFID tag
which is a first embodiment of the electronic device.
[0025] FIG. 1A is a top view of the peripheral part of a circuit
component 110 in the RFID tag 100, while FIG. 1B is a sectional
view along line A-A in FIG. 1A, in the RFID tag 100.
[0026] The RFID tag 100 illustrated in FIGS. 1A and 1B exchanges
information with external equipment, such as a reader/writer, in a
non-contact fashion with electric waves. This RFID tag 100 has a
structure such that the circuit component 110, in which a circuit
for communicating with the aforementioned external equipment
through an antenna pattern 122 for electric wave communications is
built, is mounted on a wiring substrate 120 in which a base 121
made of a PET film is overlaid with the antenna pattern 122. The
base 121, the antenna pattern 122, and the circuit component 110
correspond respectively to examples of a substrate, a wiring
pattern, and a circuit component in the fundamental aspect of the
electronic device.
[0027] The circuit component 110 includes four bumps 111 each of
which is electrically joined to the circuit, and the antenna
pattern 122 on the wiring substrate 120 has two connection ends
122a each of which is electrically connected with one of the bumps
111. In addition, the electrical connection between the circuit
built in the circuit component 110 and the antenna pattern 122 on
the wiring substrate 120 is performed by the electrical connections
between two diagonally located bumps of the four bumps 111 and the
connection ends 122a at positions corresponding to the diagonally
located bumps 111, as illustrated in FIG. 1A. The bumps 111 and the
connection ends 122a correspond respectively to examples of bumps
and connection ends in the fundamental aspect of the electronic
device.
[0028] Further, in the RFID tag 100, the connections between the
bumps 111 and the connection ends 122a are performed by conductive
adhesive portions 130 which fix the circuit component 110 onto the
surface of the wiring substrate 120, and which electrically connect
the two bumps 111 and the two connection ends 122a in one-to-one
correspondence to each other. The conductive adhesive portions 130
correspond to an example of conductive members in the fundamental
aspect of the electronic device.
[0029] In this embodiment, in the base 121, a penetrating hole
portion 123 in which a penetrating hole is formed is juxtaposed on
the right side of the right connection end 122a as seen in FIG. 1,
and at a position spaced away from the connection end 122a.
Further, a recess portion 124 in which a recess is formed is
juxtaposed on the left side of the left connection end 122a as seen
in the figures, and at a position spaced away from the connection
end 122a. Here, the penetrating hole portion 123 and the recess
portion 124 correspond respectively to examples of guide sections
in the fundamental aspect of the electronic device. Also, the
penetrating hole portion 123 and the recess portion 124 correspond
respectively to examples of the "substrate portion where the
penetrating hole is formed in the substrate" and the "substrate
portion where the recess is formed in the substrates" in the
applied aspect of the electronic device.
[0030] The circuit component 110 is mounted on the wiring substrate
120 in such a way that the connection ends 122a of the wiring
substrate 120 and/or the bumps 111 of the circuit component 110 are
each coated with the conductive adhesive portions 130, that the
circuit component 110 is provided on the wiring substrate 120 with
the bumps 111 and the connection ends 122a opposed in a one-to-one
correspondence, and that the circuit component 110 is pressed onto
the wiring substrate 120 under a specific low load. On this
occasion, the conductive adhesive portions 130 between the bumps
111 and the connection ends 122a are forced out of the intervals
between the connection ends 122a and the bumps 111 and spread to
the peripheral parts of these connection ends, by the pressing of
the circuit component 110 against the wiring substrate 120. Here in
this embodiment, the penetrating hole portion 123 and the recess
portion 124 draw the conductive adhesive portions 130 forced out of
the intervals between the connection ends 122a and the bumps 111
owing to capillarity. As a result, most of the conductive adhesive
portion 130 forced out of the interval between the right connection
end 122a and the bump 111 seen in FIG. 1 is guided to the right
side of the connection end 122a by the penetrating hole portion
123. On the other hand, most of the conductive adhesive portion 130
forced out of the interval between left connection end 122a and the
bump 111 seen in FIG. 1 is guided to the left side of the
connection end 122a by the recess portion 124. Thus, the conductive
adhesive portions 130 forced out of the intervals between the
connection ends 122a and the bumps 111 in the right and left sides
(as seen in FIG. 1) are separated from each other, and the contact
between both the conductive adhesive portions 130 is avoided. Thus,
short-circuiting between the connection portion of the bump 111 and
the right connection end 122a and the connection portion of the
bump 111 and the left connection end 122a can be reliably
avoided.
[0031] Here, regarding the fundamental aspect of the electronic
device, the following applied aspect is preferable:
[0032] At least one of the guide sections is a dummy pattern which
is provided on the substrate separately from the connection end and
in juxtaposition to the connection end.
[0033] In accordance with the preferable applied aspect, a fluid on
a substrate that has a pattern can be effectively guided along the
conductive member by utilizing the general property that the fluid
is liable to flow along the pattern.
[0034] Now, the fundamental aspect and a second embodiment which is
a practicable embodiment for the electronic device according to the
applied aspect will be described.
[0035] The second embodiment differs from the first embodiment in
how to guide the conductive adhesive portions being examples of the
conductive members forced out of the intervals between the
connection ends and the bumps. Now, the second embodiment will be
described by focusing on the points of difference from the first
embodiment.
[0036] FIGS. 2A and 2B are views of an RFID tag which is a second
practicable embodiment for the electronic device. In FIGS. 2A and
2B, elements equivalent to those illustrated in FIGS. 1A and 1B are
indicated by affixing the same numerals and signs as in FIGS. 1A
and 1B. Thus, the equivalent elements shall be omitted from
repeated description.
[0037] FIG. 2A is a top view of the peripheral part of a circuit
component 110 in the RFID tag 200, while FIG. 2B is a sectional
view along line B-B in FIG. 2A, in the RFID tag 200.
[0038] In the RFID tag 200 illustrated in FIGS. 2A and 2B, on the
base 211 of a wiring substrate 210, a first independent dummy
pattern 212 is juxtaposed on the right side of a right connection
end 122a as seen in FIG. 2, and at a position spaced away from the
connection end 122a. Further, a second independent dummy pattern
213 is juxtaposed on the left side of a left connection end 122a as
seen in FIG. 2, and at a position spaced away from this connection
end 122a. Here, the first independent dummy pattern 212 and the
second independent dummy pattern 213 correspond respectively to
examples of guide sections in the fundamental aspect of the
electronic device. Also, the first independent dummy pattern 212
and the second independent dummy pattern 213 correspond to examples
of dummy patterns in the applied aspect of the electronic
device.
[0039] The first independent dummy pattern 212 is an isolated
pattern which is arranged on the right side of the right connection
end 122a as seen in FIG. 2. The shape of the dummy pattern 212 is
similar to a right square bracket where the top of the dummy
pattern 212 (as seen in FIG. 2A) extends rightwards, bends
downwards and extends downwards for a length that is longer than
the top portion, and then bends leftwards and extends for a length
that approximates the length of the top portion. The second
independent dummy pattern 213 is an isolated pattern arranged on
the left side of the left connection end 122a as seen FIG. 2, and
has a cruciform shape.
[0040] In this embodiment, the first independent dummy pattern 212
and the second independent dummy pattern 213 draw conductive
adhesive portions 130 forced out of the interval between the
connection ends 122a and the bumps 111, by utilizing the general
property that the fluid on the substrate having a pattern is liable
to flow along the pattern. As a result, most of the conductive
adhesive portion 130 forced out of the interval between the right
connection end 122a and the bump 111 seen in FIG. 2 is guided to
the right side of this connection end 122a by the first independent
dummy pattern 212. On the other hand, most of the conductive
adhesive portion 130 forced out of the interval between the left
connection end 122a and the bump 111 seen in FIG. 2 is guided to
the left side of this connection end 122a by the second independent
dummy pattern 213. Thus, the conductive adhesive portions 130
forced out of the intervals between the connection ends 122a and
the bumps 11 seen in FIG. 2 are separated from each other, and
contact between both of the conductive adhesive portions 130 is
avoided. Thus, the short-circuiting between the connection portion
between the bump 111 and the right connection end 122a and the
connection portion between the bump 111 and the left connection end
122a may be reliably avoided.
[0041] Here, regarding the fundamental aspect of the electronic
device, the following applied aspect is preferable:
[0042] At least one of the guide sections is a dummy wiring line
which is placed in continuation to a connection end on the
substrate.
[0043] In accordance with the preferable applied aspect, the
conductive member can be guided more effectively by utilizing the
general property that a fluid on a substrate having a pattern is
liable to flow along the pattern, and by continuing the dummy
wiring line for guiding the conductive member to the connection end
by the use of such a property.
[0044] Now, the fundamental aspect and a third embodiment which is
a practicable embodiment for the electronic device according to the
applied aspect will be provided.
[0045] The third embodiment differs from the foregoing first and
second embodiments in how to guide the conductive adhesive portions
being examples of the conductive members that have been forced out
of the interval between the connection ends and the bumps. Now, the
third embodiment will be described by focusing on the points of
difference from the first and second embodiments.
[0046] FIGS. 3A and 3B are views of an RFID tag which is a third
practicable embodiment for the electronic device. In FIGS. 3A and
3B, elements equivalent to those shown in FIGS. 1A and 1B are
indicated by affixing the same numerals and signs as in FIGS. 1A
and 1B. Thus, the equivalent elements shall be omitted from
repeated description.
[0047] FIG. 3A is a top view of the peripheral part of a circuit
component 110 in the RFID tag 300, while FIG. 3B is a sectional
view along line C-C in FIG. 3A, in the RFID tag 300.
[0048] In the RFID tag 300 shown in FIGS. 3A and 3B, on the base
311 of a wiring substrate 310, a first extension dummy pattern 312
which extends rightwards in continuation from a right connection
end 122a as seen in FIG. 3 is provided. Further, a second extension
dummy pattern 313 which extends leftwards in continuation from a
left connection end 122a as seen in FIG. 3 is provided. In this
embodiment, the first extension dummy pattern 312 has a pattern
shape in which the pattern stretches spirally on the right side of
the right connection end 122a as seen in FIG. 3. The second
extension dummy pattern 313 is formed of two rectilinear patterns
which stretch leftwards from the left connection end 122a as seen
in FIG. 3. The first extension dummy pattern 312 and the second
extension dummy pattern 313 correspond respectively to examples of
guide sections in the fundamental aspect of the electronic device.
Also, the first extension dummy pattern 312 and the second
extension dummy pattern 313 correspond respectively to examples of
dummy wiring lines in the applied aspect of the electronic
device.
[0049] In this embodiment, since the first dummy pattern 312 and
the second dummy pattern 313 are provided in continuation to the
connections ends 122a, the first dummy pattern 312 and the second
dummy pattern 313 forcefully guide the conductive adhesive portion
130 that is forced out of the interval between the connection ends
122a and the bumps 111 by using the general property that fluid is
liable to flow along a pattern on a substrate when flowing on a
substrate. As a result most of the conductive adhesive portion 130
forced out of the interval between the right connection end 122a
and the bump 111 seen in FIG. 3 is guided to the right side of this
connection end 122a by the first extension dummy pattern 312.
Similarly, most of the conductive adhesive portion 130 forced out
of the interval between the left connection end 122a and the bump
111 seen in FIG. 3 is guided to the left side of this connection
end 122a by the second extension dummy pattern 313. Thus, the
conductive adhesive portions 130 forced out of the intervals
between the connection ends 122a and the bumps 111 seen in FIG. 4
are separated from each other, and contact between both the
conductive adhesive portions 130 is avoided, so that
short-circuiting between the connection portion of a bump 111 and
the right connection end 122a and the connection portion of a bump
111 and the left connection end 122a can be reliably avoided.
[0050] Here, regarding the fundamental aspect of the electronic
device stated above, the following application aspect is
preferable:
[0051] At least one of the guide sections is provided on the side
of the periphery of the connection end which faces the other
connection end.
[0052] In accordance with the preferable application aspect,
conductive members are guided in directions in which they approach
each other, while avoiding contact between the conductive members
which correspond to the plurality of connection ends, whereby the
area of those parts of the substrate which are covered with the
conductive members can be suppressed, so that the efficient
packaging of the circuit component is permitted.
[0053] Now, the fundamental aspect and a fourth embodiment which is
a practicable embodiment for the electronic device according to the
applied aspect will be described.
[0054] The fourth embodiment differs from the foregoing first to
third embodiments in how to guide the conductive adhesive portions
being examples of the conductive members forced out of the
intervals between the connection ends and the bumps. Now, the
fourth embodiment will be described by focusing on the points of
difference from the first to third embodiments.
[0055] FIGS. 4A and 4B are model views showing an RFID tag which is
the fourth practicable embodiment for the electronic device. In
FIGS. 4A and 4B, elements equivalent to those shown in FIGS. 1A and
1B are indicated by affixing the same numerals and signs as in
FIGS. 1A and 1B. Thus, the equivalent elements shall be omitted
from repeated description.
[0056] FIG. 4A is a top view of the peripheral part of the circuit
component 110 in the RFID tag 400, while FIG. 4B is a sectional
view along line D-D in FIG. 4A, in the RFID tag 400.
[0057] In the RFID tag 400 shown in FIGS. 4A and 4B, on the base
411 of a wiring substrate 410, an arc-shaped penetrating hole
portion 412 in which an arc-shaped penetrating hole is provided at
a position under the circuit component 110 is juxtaposed on the
left side of a right connection end 122a as seen in FIG. 4.
Furthermore, an arc-shaped recess portion 413 in which an
arc-shaped recess is provided at a position spaced away from a left
connection end 122a as seen FIG. 4 is juxtaposed on the right side
of the left connection end 122a. In this embodiment, the arc-shaped
penetrating hole portion 412 and the arc-shaped recess portion 413
correspond respectively to examples of guide sections in the
fundamental aspect of the electronic device.
[0058] In this embodiment, the arc-shaped penetrating hole portion
412 and the arc-shaped recess portion 413 draw the conductive
adhesive portions 130 forced out of the intervals between the
connection ends 122a and the bumps 111. As a result, most of the
conductive adhesive portion 130 forced out of the interval between
the right connection end 122a and the bump 111 seen in the FIG. 4
is guided to the right side of the connection end 122a by the
arc-shaped penetrating hole portion 412. Similarly, most of the
conductive adhesive portion 130 forced out of the interval between
the left connection end 122a and the bump 111 seen in FIG. 4 is
guided to the left side of this connection end 122a by the
arc-shaped recess portion 413. Thus, the conductive adhesive
portion 130 forced out of the interval between the right connection
end 122a and the bump 111 seen in FIG. 4 and the conductive
adhesive portion 130 forced out of the interval between the left
connection end 122a and the bump 111 seen in FIG. 4 do not contact
each other even though they approach each other, so that
short-circuiting between the connection portion of a bump 111 and
the right connection end 122a and the connection portion of a bump
111 and the left connection end 122a can be reliably avoided. Also,
in this embodiment, the conductive adhesive portions 130 forced out
of the intervals between the connection ends 122a and the bumps 111
are guided towards each other, so that the area of the parts of the
wiring substrate 410 which are covered with the conductive adhesive
portions 130 is reduced, and structurally the circuit component 110
may be efficiently mounted on the wiring substrate 410.
[0059] RFID tags have been used as examples for the embodiments of
the electronic device. However, the electronic device is not
restricted as such, and the embodiment may also correspond to a
general electronic device in which a circuit component having a
built-in circuit is packaged on a wiring substrate, for example, a
circuit board that is mounted in a portable telephone or computer
or a general domestic electric product.
[0060] RFID tags in which the circuit component is exposed when
packaged on the wiring substrate have been used as an example in
the embodiments of the electronic device. However, the electronic
device is not restricted as such, and may be, for example, an
electronic device in which the circuit component packaged on the
wiring substrate is covered with a specific resin material.
[0061] Also, in the above, the RFID tags in each of which an
interval exists between the circuit component and the wiring
substrate have been used as examples in the embodiments of the
electronic device. However, the electronic device is not restricted
as such, and may be, for example, an electronic device in which a
specific underfill resin is provided between the circuit component
and the wiring substrate.
[0062] Also, a recess provided in the base of the wiring substrate
has been used as an example of a guide section in the fundamental
aspect of the electronic device. However, the guide section in the
fundamental aspect is not restricted as such, and may be, for
example, a recess portion on a wiring pattern in which a recess is
provided by etching a recess in a place spaced away from the
connection end with the bump or in a place continuous to the
connection end, the wiring pattern being thickly formed on the
base.
[0063] A combination of the recess portion and the penetrating hole
portion which are provided in the base of the wiring substrate, a
combination of the independent dummy patterns which are formed near
the connection ends, and a combination of the extension dummy
patterns which are continuous from the connection ends, have been
used as examples of the guide sections in the fundamental aspect of
the electronic device. However, the guide sections in the
fundamental aspect are not restrictive as such, and the guide
sections may be, for example, a combination of a recess portion or
a penetrating hole portion and the independent dummy pattern, a
combination of a recess portion or a penetrating hole portion and
the extension dummy pattern, or a combination of the independent
dummy pattern and the extension dummy pattern.
[0064] As described above, according to the fundamental aspect of
the electronic device, a circuit component may be mounted on a
wiring substrate in a state where short-circuiting between the
electrical connection portions of bumps and connection ends based
on conductive members is reliably avoided.
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